Fix sxhash-equal on bytecodes, markers, etc.

Problem reported by Pip Cet (Bug#38912#14).
* doc/lispref/objects.texi (Equality Predicates):
Document better when ‘equal’ looks inside objects.
* doc/lispref/windows.texi (Window Configurations):
Don’t say that ‘equal’ looks inside window configurations.
* etc/NEWS: Mention the change.
* src/fns.c (internal_equal):
Do not look inside window configurations.
(sxhash_obj): Hash markers, byte-code function objects,
char-tables, and font objects consistently with Fequal.
* src/window.c (compare_window_configurations):
Now static.  Remove last argument.  Caller changed.
* test/lisp/ffap-tests.el (ffap-other-window--bug-25352):
Use compare-window-configurations, not ‘equal’.
* test/src/fns-tests.el (test-sxhash-equal): New test.

1 files changed, 31 insertions, 21 deletions

diff --git a/src/fns.c b/src/fns.c
index 4a0a8fd96d8..4a463a8feb2 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -2434,6 +2434,9 @@ internal_equal (Lisp_Object o1, Lisp_Object o2, enum equal_kind equal_kind,
            same size.  */
         if (ASIZE (o2) != size)
           return false;
+
+        /* Compare bignums, overlays, markers, and boolvectors
+           specially, by comparing their values.  */
         if (BIGNUMP (o1))
           return mpz_cmp (*xbignum_val (o1), *xbignum_val (o2)) == 0;
         if (OVERLAYP (o1))
@@ -2454,7 +2457,6 @@ internal_equal (Lisp_Object o1, Lisp_Object o2, enum equal_kind equal_kind,
                     && (XMARKER (o1)->buffer == 0
                         || XMARKER (o1)->bytepos == XMARKER (o2)->bytepos));
           }
-        /* Boolvectors are compared much like strings.  */
         if (BOOL_VECTOR_P (o1))
           {
             EMACS_INT size = bool_vector_size (o1);
@@ -2465,11 +2467,6 @@ internal_equal (Lisp_Object o1, Lisp_Object o2, enum equal_kind equal_kind,
               return false;
             return true;
           }
-        if (WINDOW_CONFIGURATIONP (o1))
-          {
-            eassert (equal_kind != EQUAL_NO_QUIT);
-            return compare_window_configurations (o1, o2, false);
-          }
 
         /* Aside from them, only true vectors, char-tables, compiled
            functions, and fonts (font-spec, font-entity, font-object)
@@ -4703,22 +4700,35 @@ sxhash_obj (Lisp_Object obj, int depth)
       hash = sxhash_string (SSDATA (obj), SBYTES (obj));
       break;
 
-      /* This can be everything from a vector to an overlay.  */
     case Lisp_Vectorlike:
-      if (BIGNUMP (obj))
-        hash = sxhash_bignum (obj);
-      else if (VECTORP (obj) || RECORDP (obj))
-        /* According to the CL HyperSpec, two arrays are equal only if
-           they are `eq', except for strings and bit-vectors.  In
-           Emacs, this works differently.  We have to compare element
-           by element.  Same for records.  */
-        hash = sxhash_vector (obj, depth);
-      else if (BOOL_VECTOR_P (obj))
-        hash = sxhash_bool_vector (obj);
-      else
-        /* Others are `equal' if they are `eq', so let's take their
-           address as hash.  */
-        hash = XHASH (obj);
+      {
+        enum pvec_type pvec_type = PSEUDOVECTOR_TYPE (XVECTOR (obj));
+        if (! (PVEC_NORMAL_VECTOR < pvec_type && pvec_type < PVEC_COMPILED))
+          {
+            /* According to the CL HyperSpec, two arrays are equal only if
+               they are 'eq', except for strings and bit-vectors.  In
+               Emacs, this works differently.  We have to compare element
+               by element.  Same for pseudovectors that internal_equal
+               examines the Lisp contents of.  */
+            hash = sxhash_vector (obj, depth);
+            break;
+          }
+        else if (pvec_type == PVEC_BIGNUM)
+          hash = sxhash_bignum (obj);
+        else if (pvec_type == PVEC_MARKER)
+          {
+            ptrdiff_t bytepos
+              = XMARKER (obj)->buffer ? XMARKER (obj)->bytepos : 0;
+            hash = sxhash_combine ((intptr_t) XMARKER (obj)->buffer, bytepos);
+            hash = SXHASH_REDUCE (hash);
+          }
+        else if (pvec_type == PVEC_BOOL_VECTOR)
+          hash = sxhash_bool_vector (obj);
+        else
+          /* Others are 'equal' if they are 'eq', so take their
+             address as hash.  */
+          hash = XHASH (obj);
+      }
       break;
 
     case Lisp_Cons: